Answer:

Step-by-step explanation:
→ State the gradient formula
( y₂ - y₁ ) ÷ ( x₂ - x₁ )
→ Find x₁ , x₂ , y₁ and y₂
x₁ = 4 , x₂ = 12 , y₁ = 9 and y₂ = 20
→ Substitute in the values

→ Simplify

If its multiplcation
731700
if its addition
1895
im sorry if im wrong but im just trying to help out and please correct me if ime wrong
Answer:
It is necessary four parameters.
Step-by-step explanation:
Since the augmented matrix of the consistent system has rank equal to three then the number of free variables is (number of unknows)-rank then there are 7-3=4 free variables. This means that are necessary four parameter to specify all solutions.